Impact machines for working by the employment of high kinetic energy are machines for working in the first place metal, such as cutting, punching, and plastic forming of powder components, powder compaction, and similar operations, in which the velocity of a ram, which may consist of a hydraulic piston, may be essentially higher than in conventional presses. Also polymeric and ceramic working materials can be conceived, as well as various composites of metals, polymers and ceramic materials. The working principle is based on the development of a very high kinetic energy of short duration instead of a high static press force of long duration.
Impact machines are well suited for the manufacture of annular articles, such as gears, bushings, and the like, in a closed mould cavity. However, it is a problem to get the formed body out of the mould cavity without damaging it. This particularly is true for articles which are formed of metal powder and which have not been consolidated through coalescence of the powder, i.e. welding of the powder grains, to form a well united, strong body. Therefore, it is a particularly great risk for damages when articles are manufactured, which are formed of powder, but also articles which are formed of a solid blank can crack or form layers, when they are pushed out of the mould cavity. Besides, it has not been possible to perform the manufacture in a rational mode according to prior art, i.e. in a mode which provides the high production capacity which is required in the first place for the manufacture of mass products, such as gears, bushings, and the like. For example it is a problem to remove the mandrel out of the formed article by known technique.